The Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus that, despite the life-time rapport typically achieved with its human host, can be associated with benign (infectious mononucleosis) and malignant (Burkitt's lymphoma, Hodgkin's lymphoma, primary central nervous system lymphoma) lymphoproliferative diseases. The overall objective of this grant is to understand molecular mechanisms by which EBV causes disease and their inter-relatedness to modes of viral persistence in the memory B lymphocyte reservoir. Physiologic signaling via the B cell antigen receptor (surface immunoglobulin) has major implications for the fate of any infected B cell, leading to cell proliferation and differentiation or, conversely, apoptosis. Because we showed up-regulation of recombinase activating genes RAG1 and RAG2 upon EBV infection of mature B cells, we now hypothesize that virus diversifies the B cell antigen receptor through induction of secondary immunoglobulin gene rearrangements as a means of assuring adequate survival signaling in infected cell progeny. Renewed V(D)J recombination outside the selective environment of bone marrow or germinal centers has potential pathogenic consequences that include auto-immunity, lymphoproliferation and chromosomal damage. The specific aims to test our hypothesis are: 1) to determine if secondary rearrangements of immunoglobulin variable region genes occur as a consequence of RAG induction by Epstein-Barr virus; 2) to determine if RAG1 and RAG2 are expressed in human peripheral blood lymphocytes in vivo as a consequence of acute EBV infection; 3) to analyze EBV DNA integration as a marker of illegitimate recombination prompted by viral induced RAG expression; 4) to determine the mechanism by which RAG1 and RAG2 are up regulated by latency protein EBNA1. The use of recombinant EBV expressing green fluorescent protein allows rapid selection of infected cells now capable of expressing RAG; concurrent analysis by flow cytometry for altered surface immunoglobulin; detection by PCR of broken DNA ends or excision circles that are byproducts of V(D)J recombination; and subsequent analysis for chromosomal abnormalities from aberrant RAG.